1. Field of the Invention
The present invention relates to a writing implement. In detail, the invention relates to a writing implement which comprises a shaft barrel storing ink in an interior portion thereof and a plug body (for example, a tail plug or a pen point hold body) removably mounted on one end of the shaft barrel. In the present invention, a term "front" means the pen point side of the writing implement, whereas a term "rear" means the tail plug side thereof. Also, an expression "front surface" means the axial-direction outer surface of the writing implement, whereas an expression "back surface" means the axial-direction inner surface thereof.
2. Description of the Related Art
Conventionally, for example, in Japanese Patent Unexamined Publication No. Hei. 11-48679, there is disclosed a writing implement in which, for the purpose of removing an ink storing body stored into an interior portion of a shaft barrel, a tail plug is removably mounted on an opening formed in a rear end portion of the shaft barrel. Further, between a flange portion of the tail plug and the rear end portion of the shaft barrel, there is formed a groove (a cutaway portion) into which a coin such as a ten-yen coin or a tool can be engaged. By engaging the coin into the groove, the tail plug can be forced open.
Also, in the above-cited publication, there is also disclosed a writing implement in which a pen point hold body including a pen point is removably mounted on an opening formed at a front end portion of a shaft barrel. Between a flange portion of the pen point hold body and the front end portion of the shaft barrel, there is formed a groove (a cutaway portion) similar to the above-mentioned structure.
However, in the above-mentioned conventional writing implements, since the groove for forcible opening is shallow inwardly in a diameter direction thereof, when forcing open the tail plug or pen point hold body, the coin or tool can be inserted into the groove only in a small amount. Namely, the tail plug or pen point hold body cannot be forced open easily; or, a large force is necessary to force open the tail plug or pen point hold body. Therefore, there is a fear that the end portion of the shaft barrel, the flange portion of the tail plug, or the flange portion of the pen point hold body can be damaged.